Device for Joining Flat Metal Products Passing Successively Into a Strip Processing Plant

ABSTRACT

A device for joining metal strips passing successively into a strip processing plant includes two cutting punches having a respective cutting edge which is associated with a cutting edge of the respective other cutting punch. The cutting punches are movable along a cutting axis in a cutting motion to produce an undetachable join in an adjoining region by deformation. In the same position with respect to the cutting axis, the cutting edges of the cutting punches define a cutting gap which extends in the transverse direction and occupies a gap width in a width direction oriented at a right angle to the transverse direction and to the cutting axis. The cutting edges include an acute angle with the transverse direction, viewed from the cutting direction and in that the cutting punches are movable relative to one another in the transverse direction of the cutting gap to change the gap width.

The invention relates to a device for joining metal strips passing successively into a strip processing plant.

This type of device usually comprises at least two cutting punches. The cutting punches each have at least one cutting edge which is associated with a cutting edge of the respective other cutting punch. To perform the cutting procedure, at least one of the punches can be moved in a cutting motion along a cutting axis towards the respective other punch. The metal strips to be joined together are then connected by making, in one step, at least one cut in two superimposed end portions of the metal strips and then deforming a region of the end portions which adjoins the cut such that an undetachable join is produced between the flat products. The cutting procedure takes place in a cutting gap which, when the cutting edges meet at the same height with respect to the cutting axis during the cutting motion thereof is delimited by the cutting edges such that it extends in a direction oriented transversely to the cutting axis and occupies a gap width in a width direction which is respectively oriented at a right angle to the transverse direction and to the cutting axis.

The strip material processed in a device according to the invention typically consists of a metal material such as normal steel, stainless steel, aluminium material or other non-ferrous metal materials.

Devices of the type according to the invention are used in processing plants in which the metal strips are subjected to a heat treatment or surface treatment, passing continuously through the treatments, for example. The metal strips, usually supplied as coils, are unwound, they pass through the processing plant and are finally rewound into coils in a coiling station located at the end of the processing plant. The coiling station and driver stations optionally provided in the processing plant are configured such that they pull the metal strips through the processing plant.

To allow uninterrupted operation here, the end of the metal strip being processed in the processing plant is firmly joined with the beginning of a newly delivered coil which is ready to be processed. The strip being processed then pulls the new strip into the processing plant until it has reached the coiling station. Here, the strips are separated and the new strip is wound into a new coil.

Thus, the prerequisite for a new strip being reliably drawn into the strip processing plant is a join between the beginning of a strip and the end of a strip, which join also withstands high tensile loads. At the same time, the join has to be produced during operation, i.e. fast enough so that the strip run is not disturbed.

To satisfy these requirements, the strips to be joined together are arranged such that their mutually associated end portions overlap in devices of the type concerned here. Thereafter, a joining procedure is carried out in which a locally limited deformation of the end portions is produced by the effect of force against at least one of the broad sides of the strips. Accordingly, the join produced thus is made non-positively or positively in the manner of a punch join, in which cuts or perforations are made in the superimposed strip portions. Associated with the joining procedure, the regions of the strips adjoining the perforation or the respective cut are deformed such that the metal sheets hook into each other. If necessary, this hooking procedure can be reinforced in a further processing step to ensure that the join produced thus withstands the forces arising during the subsequent processing of the joined strips. Devices which perform this procedure are therefore also known in the technical jargon as “tack punching devices”.

The cut required to produce a tack-punch join is performed by the cutting edges, moved relative to one another of punching tools, at least one of which is movable towards the respective other along a cutting axis. The accuracy with which the cutting punches make the cut substantially depends on the distance between the cutting edges at the time of cutting, i.e. on the width of the cutting gap at the time when the cutting edges of the tools meet one another at the same height. The more precisely the cutting gap, also known as “clearance” in the technical jargon, is adjusted to the thickness of the metal strips to be joined together, the better the cutting result. If the width of the cutting gap is too big, then pinching effects and thereby undesirable edge formation ensues in the region of the cuts. However, if the clearance is too small, then burring occurs on the cut edges. In this respect, relatively large quantities of metal particles are produced which are entrained in a loose form or are still suspended on the strip into the strip processing plant. These fine shavings and other shearing products, also known as “flitter” in the technical jargon can damage movable parts there or, if they accumulate on the circumferential surfaces of deflection rollers or guide rollers which come into contact with the strip, can even impair the surface quality of the processed metal strip.

To minimise the amount of flitter which is produced during cutting and is entrained into the processing plant, it is proposed in DE 10 2005 037 182 A1 to stick down the punched joins, provided there for joining the strips, by means of adhesive strips so that during the punching procedure, no flitter particles and burrs can break off. However, the expense associated with this measure is undesirable in a fast-running continuous operation of a strip processing plant. Furthermore, this solution proves to be unsuitable for joining strips which pass into the strip processing plant at high temperatures.

Against the background of the prior art described above, the object of the invention was to provide a device, using which metal strips which are to be drawn into a strip processing plant, can be joined together in an operationally reliable manner with a minimum amount of flitter being produced.

The invention achieves this object by the configuration, stated in claim 1, of a device for joining two metal strips.

Advantageous configurations of the invention are set out in the dependent claims and will be described in detail in the following, as will the general inventive concept.

Thus, a device according to the invention for joining metal strips passing successively into a strip processing plant comprises at least two cutting punches, each of which has at least one cutting edge which is associated with a cutting edge of the respective other cutting punch. The cutting punches are movable towards one another along a cutting axis in a cutting motion in order to make at least one cut in two superimposed end portions of the metal strips to be joined together and to deform a region, adjoining the cut, of the end portions such that an undetachable join is produced between the metal strips. When their cutting edges meet at the same height in respect of the cutting axis during the cutting motion, the cutting punches define with their cutting edges a cutting gap which extends in a direction transverse to the cutting axis and occupies a gap width in a width direction oriented at a right angle to the transverse direction and to the cutting axis.

According to the invention, the cutting edges, defining the respective cutting gap, of the cutting punches include an acute angle with the transverse direction of the cutting gap, viewed from the cutting direction. At the same time, the cutting punches can be moved relative to one another in the transverse direction of the cutting gap to change the gap width.

In a device according to the invention, an adjusting means is thus provided by which at least one of the tools provided for making the cut in the strips to be joined together can be moved in a direction transverse to the cutting direction in order to adjust the clearance. As a result of the orientation of the cutting edges which slants at an acute angle relative to the adjusting direction, by moving in a transverse direction, a proportional approach or distancing of the mutually associated cutting edges of the cutting punches is achieved. Thus, with a projection in a plane oriented normally to the cutting axis, there results an adjustment dQ of the cutting punch position, in terms of amount a change dB of the cutting gap width, measured in the width direction of the cutting gap, oriented at a right angle to the transverse direction, of dB in the cutting gap width of dB=dQ×tan (β), where “β” denotes the angle included by the cutting edge with the transverse direction. When the cutting edges of the mutually associated cutting punches are oriented in parallel, the clearance of the cutting gap changes accordingly by the amount dW=dQ×cos (90−β).

In principle, it is possible to join the metal strips, to be drawn successively into the processing plant, in only one joining zone. This can be expedient for very narrow strips. However, with wider metal strips, it will be necessary to produce a plurality of joining zones for a secure join. For this purpose, each cutting punch of a device according to the invention can have a plurality of cutting edges arranged next to one another in the width direction. Here as well, each cutting edge of one cutting punch is associated with a cutting edge of the other cutting punch. To make the cut, the punches then mesh together in the manner of teeth so that a cut is simultaneously made in the strips to be joined together at a number of cutting points corresponding to the cutting edges of each of the cutting punches.

If each of the cutting punches has a plurality of cutting edges, the cutting edges of the respective punch can be oriented parallel to one another in each case. The cuts made in the metal strips are then accordingly oriented parallel to one another, obliquely to the longitudinal extent of the metal strips. However, to form a fixed positive join, it can be expedient if cutting edges, in each case adjacent to one another, of the cutting punches are arranged such that they run towards one another in a V shape, observed in a plan view from the cutting direction. Triangular joining points are then produced in the metal strips. This shape promotes the production of undercuts and clamping effects, reinforced by the tensile forces which, during operation, act on the metal strips in the longitudinal direction thereof.

The tendency to form hooking effects can be further increased in the region of the joins formed by a device according to the invention in that provided on the cutting punches is a respective cutting edge which is divided in each case by an offset into at least two cutting edge portions which are joined by a connecting portion and are oriented in a mutually offset manner in the width direction of the cutting gap. Here as well, the cutting edges, provided with the offset cutting edge portions, of the cutting punches are naturally associated with one another to ensure a correct cutting procedure with an optimised cutting gap width. Offsetting the cutting edge portions produces a shoulder on the cutting edges of the superimposed metal strips. Due to the tensile loads prevailing in the longitudinal direction of the metal strips, these portions hook together in the manner of catches and thus prevent the strips from moving relative to one another in their longitudinal direction. In addition, the production of a positive join of this type can be promoted in that the cutting edge corner points at which the respective connecting portion merges into the cutting edge portions, connected thereto, of the respective cutting edge, are arranged in a mutually offset manner in the transverse direction,

A simple adaptation to different processing conditions or a simple replacement in the case of wear can be allowed in that cutting punch elements supporting the cutting edges of the respective cutting punch are held in a releasable manner.

The displacement provided according to the invention for adjusting the cutting gap width can be carried out in any suitable manner. This can be performed in a particularly practice-oriented manner when at least the cutting punch is mounted displaceably in the transverse direction and when an adjusting means is provided to move this punch. This adjusting means can also be realised in any suitable manner, for example by hydraulic adjusting cylinders.

A particularly robust adjusting means which, at the same time, is economical to produce, for moving the respective cutting punch is produced when the adjusting means is formed by a wedge element which can be moved in its longitudinal direction and the longitudinal sides of which include between them an acute angle and the associated punch is supported on one longitudinal side thereof, while the wedge element is supported by its remote longitudinal side on a support means mounted in a stationary manner. With an adjusting means of this type, each displacement of the wedge element in the longitudinal direction thereof results in a movement, oriented transversely to this displacement, of the tool.

In this respect, the adjustable tool can be optimally supported in that it is supported on two opposite sides by a respective wedge element, the wedge surfaces of the wedge elements being oriented parallel to one another. In this case, one wedge element is arranged on one longitudinal side and the other wedge element is arranged on the longitudinal side of the cutting punch opposite the first longitudinal side in the transverse direction of the cutting gap. Since the wedge elements are each displaced in the same direction, the respective cutting punch is always guided in a clearly defined fashion between the wedge elements in the manner of a parallel guidance.

To facilitate a particularly fine gradation of the adjustment of the cutting gap width by a longitudinal displacement of the wedge element, it is possible to provide a greater number of wedge elements which each cooperate such that each displacement of one of the wedge elements causes a displacement of the cutting punch, supported on the wedge elements, in the transverse direction.

A configuration of the invention which is economical to produce and is at the same time practice-oriented is distinguished in that only one of the cutting punches is movable. In this case, one of the cutting punches is then fixed, based on the transverse direction of the cutting gap, while the other cutting punch is movable in the transverse direction of the cutting gap to adjust the cutting gap width.

Due to the relative movement of the cutting punch which takes place according to the invention in the transverse direction of the cutting gap, a clearance of the cutting gaps is adjusted which corresponds to one twentieth to one fifth, in particular one twelfth to one eighth of the averaged thickness of the metal strips to be joined together. For a typical thickness of the strips processed using a device according to the invention of 0.5-3 mm, this implies a clearance displacement range of, for example, 0.25-0.6 mm, in particular 0.063-0.375 mm. The adjustment paths which have to be travelled subject to the angle included between the cutting edges of the cutting punches and the transverse direction are correspondingly short in order to adjust the gap width which is optimum in each case.

In the following, the invention will be described in more detail with reference to schematic drawings which illustrate an embodiment.

FIG. 1 is a front view of a device for joining metal strips;

FIG. 2 is a plan view of a cutting punch used in the device according to FIG. 1;

FIG. 3 a-3 c show the cutting punch according to FIG. 2 in three different operating positions;

FIG. 4 shows an enlarged detail of the cutting punch according to FIG. 2;

FIG. 5 is a diagram of a strip processing plant respectively traversed by the metal strip to be processed in continuous operation.

The device H comprises an upper base plate 1 which is connected to a lower base plate 3 by guide columns 2.

The lower base plate 3 supports a lower cutting punch 4, while the upper base plate 1 supports an upper cutting punch 5.

The cutting punches 4, 5 each comprise a cutting punch holder 6 in which cutting punch elements 7, 8 are held in a releasable manner by suitable screw connections. Of the frame-shaped cutting punch holders of the cutting punches 4, 5, FIGS. 3 a-4 respectively only show in detail the cutting punch holder 6 of the lower punch 4.

A plurality of similar cutting punch elements 7, 8 are respectively arranged next to one another at regular intervals in the width direction B in the respective cutting punch holder 6 of the punches 4, 5.

In the example shown in the figures, the position of the lower cutting punch 4, acting in the manner of a bottom die, can be moved in direction Q, oriented transversely to the cutting direction S oriented vertically here, relative to the upper cutting punch 5. In this case, the transverse direction Q coincides with the longitudinal direction L and the conveying direction F of the metal strips M1, M2 to be joined together in device H.

In order to move the lower punch 4 with respect to the upper punch 5 which is fixed in the width direction B and in the transverse direction Q, but is movable in the cutting direction S towards the lower punch 4, the lower punch 4 has on its two opposite longitudinal sides a respective bevelled contact surface 9, against which a respective wedge element 10, 11 acts with a wedge surface 12, 13 formed on its longitudinal side associated with the upper punch 5. The bevelled contact surfaces of the punch 4 and the associated, correspondingly sloping wedge surfaces of the wedge elements 10, 11 rest closely against one another.

Attached to the base plate 3, fixed to the frame of the device H, of the lower punch 4 are longitudinal guide bars 14, 15 which are aligned parallel to one another and extend in the longitudinal direction of the wedge elements 10, 11, i.e. in the width direction B, oriented at a right angle to the transverse direction Q, of the lower punch 4. The longitudinal guide bars 14, 15 serve as supports and guides for the wedge elements 10, 11 which are supported with their longitudinal side, remote from the punch holder 6, on the respectively associated longitudinal guide bar 14, 15. At the same time, the punch holder 6 is guided on its narrow sides by lateral transverse guide bars 16, 17 oriented in the transverse direction Q. In this respect, the length of the transverse guide bars 16, 17 is restricted such that the wedge elements 10, 11 can be pushed in the width direction B along the longitudinal guide bars 14, 15 beyond said longitudinal guide bars 14, 15.

In this manner, as indicated by the directional arrows P1, P2 shown in FIG. 2 and as demonstrated with reference to FIGS. 3 a-3 c, the position of the lower punch 4 can be changed in the transverse direction Q relative to the upper punch 5 by moving the wedge elements 10, 11. If the wedge elements 10, 11 are jointly moved in the direction of one lateral guide bar 16 (directional arrow P1), the cutting punch 4 is moved out of the neutral position in which the position of its centre axis M4, oriented in the width direction B, coincides with the centre axis M3 of base plate 3 (FIG. 3 b), in the direction of the longitudinal guide bar 14 (FIG. 3 a). However, if the wedge elements 10, 11 are jointly moved in the opposite direction (directional arrow P2), the cutting punch 4 is moved in the direction of the other longitudinal guide bar 15 (FIG. 3 c).

In a plan view, the cutting punch elements 7, 8 of the punches 4, 5 have in each case on their free end face cutting edges 18, 19 (cutting punch elements 7 of the lower punch 4) and 20, 21 (cutting punch elements 8 of the upper punch 5) which run towards each other in a V shape and extend in the transverse direction Q.

The cutting punch elements 7, 8 associated with the upper punch 5 and the lower punch 4 are arranged alternately such that the mutually associated cutting edges 18, 20; 19, 21 of the punches are oriented parallel in each case. When the upper punch 5 moves towards the lower punch 4 along the cutting axis S and when the mutually associated cutting edges 18, 20; 19, 21 meet, the mutually associated cutting edges 18-21 define between them a respective cutting gap 22, 23 which, seen from the cutting direction, extends in the transverse direction Q and in the width direction B, the transverse direction Q and the width direction B being located in a plane oriented normally to the cutting axis S. In a plan view, viewed from the cutting direction S, the cutting edges 18-21 include with the transverse direction Q an acute angle β. Accordingly, the clearance WS of the cutting gaps 22, 23 is the distance measured in each case as the perpendicular on the mutually associated cutting edges 18, 20; 19, 21 (FIG. 4).

Accordingly, the width BS and, associated therewith, the clearance WS of the cutting gaps 22, 23 can be adjusted simply by jointly moving the wedge elements 10, 11 in their longitudinal direction indicated in FIG. 2 by arrows P1, P2. In the embodiment illustrated here, the clearance WS is adjusted thus, for example, to one tenth of the thickness of the metal strips M1, M2 to be joined together. If two metal strips M1, M2 of different thicknesses are joined together, the clearance WS is adjusted to one twentieth to one fifth, in particular one twelfth to one eighth of the averaged thickness of the metal strips M1, M2 (WS=F×(D1+D2)/2, where D1=thickness of one metal strip M1, D2=thickness of the other metal strip M2, F= 1/20 . . . ⅕, in particular F= 1/12 . . . ⅛, specifically F= 1/10).

For simple maintenance, an automatic exchange of the cutting punches 4, 5 is provided. For this purpose, an automatic clamping of the base plates 1 and 3 is allowed. For tensioning, a clamping bar 24 is drawn in a groove, which is T-shaped in particular, in the direction of a base frame 25 which supports the upper cutting punch 4.

The clamping bar 24 can be connected to a clamping cylinder 26 by a tension bolt. When the clamping cylinder 26 is released, a compression spring relieves the clamping bar 24, and the respective cutting punch 4, 5 is released with its associated base plate 1, 3 from the base frame 25. Thereafter, the cutting punch 4, 5 to be respectively exchanged can be transported out of the base frame 25. A drive unit 27 is used for this purpose.

The device H is incorporated into a strip processing plant A, through which strips pass continuously and the individual processing stations of which are schematically illustrated in FIG. 5. Processing plants of this type are also known as “conti-processing plants” in the technical jargon. When a newly entering metal strip M2 to be processed, which is, for example, a cold-rolled steel strip, is delivered as a coil C2 and is prepared in an unwinding station A1, a metal strip M1 is already being processed in plant A. The metal strip M1 is wound from a coil C1 in unwinding station A1.

As soon as the end of the metal strip M1 is visible, metal strip M2 is fed into plant A which can be, for example, an electrolytic coating, phosphatising and chromating plant. The metal strip M2 passes into the device H in which its front end portion is positioned, overlapping, on the rear end portion of metal strip M1. Thereafter, the joining procedure is carried out in which the device H, adjusted and operated in the manner described above, makes cuts in the superimposed end portions of the strips and at the same time the regions of the end portions between the cuts are deformed such that the metal sheets hook together. In this respect, the gap width BS of the cutting gaps 22, 23 is approximately 1/10 of the thickness of the metal strips M1, M2, so that an optimum cut is made with a minimum production of flitter.

The metal strip M2, joined thus to the metal strip M1 is pulled by the metal strip M1 through the processing stations, traversed successively in conveying direction F and listed here merely by way of example: A2 (chemical degreasing), A3 (strip dryer), A4 (electrolytic degreasing), A5 (surface activation), A6 (electrolytic coating), A7 (phosphatising), A8 (chromating), A9 (strip drying), until the coiling station A10 is reached. There, the metal strips M1, M2 are severed and the now coated metal strip M2 is wound onto a new coil.

LIST OF REFERENCE NUMERALS

-   1 upper base plate -   2 guide columns -   3 lower base plate -   4 lower cutting punch -   5 upper cutting punch -   6 cutting punch holder -   7 cutting punch elements of lower cutting punch 4 -   8 cutting punch elements of upper cutting punch 5 -   9 bevelled contact surface of cutting punch holder 6 -   10, 11 wedge elements -   12, 13 wedge surface of wedge elements 10, 11 -   14, 15 longitudinal guide bars -   16, 17 transverse guide bars -   18, 19 cutting edges of cutting punch elements 6 of lower cutting     punch 4 -   20, 21 cutting edges of cutting punch elements 7 of upper cutting     punch 5 -   22, 23 cutting gaps -   24 clamping bar -   25 base frame -   26 clamping cylinder -   27 drive unit -   A strip processing plant -   A1 unwinding stations -   A2-A9 strip processing stations of strip processing plant A -   B width direction -   BS width of cutting gaps 22, 23 -   β angle -   C1, C2 coils -   F conveying direction of metal strips M1, M2 -   H device for joining two metal strips M1, M2 -   L longitudinal direction of metal strips M1, M2 -   M1, M2 metal strips -   M3 centre axis of base plate 3 -   M4 centre axis of cutting punch 4 -   P1, P2 directional arrows (adjustment directions of wedge elements     10, 11) -   Q transverse direction -   S cutting direction -   WS clearance of cutting gaps 22, 23 

1. A device for joining metal strips passing successively into a strip processing plant, comprising at least two cutting punches, each of which has at least one cutting edge which is associated with a cutting edge of the respective other cutting punch, wherein said cutting punches are movable towards one another along a cutting axis in a cutting motion in order to make at least one cut in two superimposed end portions of the metal strips to be joined together and to deform a region, adjoining the cut, of the end portions such that an undetachable join is produced between the metal strips, and when the cutting edges of the cutting punches meet at the same height in respect of the cutting axis during the cutting motion, the cutting punches define with their cutting edges a cutting gap which extends in a transverse direction to the cutting axis and occupies a gap width in a width direction oriented at a right angle to the transverse angle and to the cutting axis, characterised in that the cutting edges, defining the respective cutting gap, of the cutting punches include an acute angle with the transverse direction of the cutting gap, viewed from the cutting direction, and in that the cutting punches can be moved relative to one another in the transverse direction of the cutting gap to vary the gap width.
 2. The device according to claim 1, wherein each cutting punch has a plurality of cutting edges arranged next to one another in the width direction.
 3. The device according to claim 2, wherein viewed in a plan view from the cutting direction, respectively mutually adjacent cutting edges of the cutting punches are arranged such that they run towards one another in a V shape.
 4. The device according to claim 1, wherein provided on the cutting punches is a respective cutting edge which is divided in each case by an offset into at least two cutting edge portions which are joined by a connecting portion and are oriented in a mutually offset manner in the width direction of the cutting gap, and in that the cutting edges, provided with the offset cutting edge portions, of the cutting punches are associated with one another.
 5. The device according to claim 4, wherein corner points of the cutting edge at which the respective connecting portion merges into the cutting edge portions, joined thereto, of the respective cutting edge are arranged in a mutually offset manner in the transverse direction.
 6. The device according to claim 1, wherein at least one of the cutting punches comprises a cutting punch holder in which cutting punch elements supporting the cutting edges of the respective cutting punch are held in a releasable manner.
 7. The device according to claim 1, wherein at least one of the cutting punches is mounted displaceably in the transverse direction and an adjusting means is provided for moving this cutting punch.
 8. The device according to claim 7, wherein the adjusting means is formed by a wedge element which is movable in a longitudinal direction and the longitudinal sides of which include between them an acute angle and the associated cutting punch is supported on one longitudinal side thereof, while the wedge element is supported with its remote longitudinal side on a stationarily mounted support.
 9. The device according to claim 8, wherein the adjusting means is formed by two similarly configured wedge elements which are oriented in opposite directions to one another.
 10. The device according to claim 9, wherein one wedge element is arranged on one longitudinal side and the other wedge element is arranged on the longitudinal side of the cutting punch opposite the first longitudinal side in the transverse direction of the cutting gap.
 11. The device according to claim 1, wherein one of the cutting punches is fixed, based on the transverse direction of the cutting gap, while the other cutting punch is movable in the transverse direction of the cutting gap to adjust the cutting gap width.
 12. The device according to claim 1, wherein due to the relative movement of the cutting punches takes place in the transverse direction of the cutting gap, a clearance of the cutting gap is adjusted which corresponds to one twentieth to one fifth of the averaged thickness of the metal strips to be joined together. 